To verify you can send a test email to port25's authentication checker:
echo test email | exim [email protected] # replies back
echo test email | exim [email protected] # replies back
echo test email | exim [email protected] \
# replies to [email protected]
In the recieved report there'll be a line:
HELO hostname: somedomain.com
Or simply add -v option:
$ echo test email | exim -v [email protected]
LOG: MAIN
<= [email protected] U=root P=local S=290
delivering 1hM501-0007Nn-7A
R: dnslookup for [email protected]
T: remote_smtp for [email protected]
Connecting to mail.dst.com [ip.add.re.ss]:25 ... connected
SMTP<< 220 dst.com ESMTP Postfix (Debian/GNU)
SMTP>> EHLO src.com
SMTP<< 250-dst.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
SMTP>> STARTTLS
SMTP<< 220 2.0.0 Ready to start TLS
SMTP>> EHLO src.com
SMTP<< 250-dst.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
SMTP>> MAIL FROM:<[email protected]> SIZE=1322
SMTP>> RCPT TO:<[email protected]>
SMTP>> DATA
SMTP<< 250 2.1.0 Ok
SMTP<< 250 2.1.5 Ok
SMTP<< 354 End data with <CR><LF>.<CR><LF>
SMTP>> writing message and terminating "."
SMTP<< 250 2.0.0 Ok: queued as 0019EEC0B6D
SMTP>> QUIT
LOG: MAIN
=> [email protected] R=dnslookup T=remote_smtp H=mail.dst.com [ip.add.re.ss] X=TLS1.0:RSA_AES_256_CBC_SHA1:32 DN="CN=dst.com"
LOG: MAIN
Completed
Alternatively, you can check the receiving MTA's log:
exim:
Received: from [ip.add.re.ss] (helo=HELO_HOSTNAME)
...
postfix:
Received: from HELO_HOSTNAME (myhostname [ip.add.re.ss])
...